Field of the Invention
The present invention relates to a technique of specifying the location of a failure in a system having a plurality of units connected by cables.
Description of the Related Art
A plurality of units are connected by cables (power cables and communication lines) inside a multifunctional peripheral (MFP) equipped with the functions of a copier, a printer, a scanner, and the like. In a case of specifying the location of a failure occurring in the MFP, the conditions of the plurality of units may be collected. In this way, the location of the failure can be specified more accurately from a narrower range. For example, in a case where a unit cannot be powered on, possible causes of that failure can be failure of that unit, as well as failure of a power supply unit, fuse blow, cable disconnection, and the like. In this case, the location of the failure can be specified by checking the power condition of the unit that cannot be powered on, as well as the power conditions of the power supply unit and other units.
In a case where diagnosis information on the inside of units is to be transferred there between, diagnosis units included in these units may be connected to each other. However, this method involves providing an additional communication line dedicated to failure diagnosis, which increases the cost. Further, if the communication line for diagnosis is added, the communication line for diagnosis itself will require diagnosis as well, which decreases the reliability. Hence, there is a demand for a technique of transferring diagnosis information between units by using an existing communication line.
Japanese Patent Laid-Open No. H05-324375(1993) discloses a technique in which diagnosis information indicating diagnosis on a unit is transferred to another unit. In the technique disclosed in Japanese Patent Laid-Open No. H05-324375(1993), the diagnosis information is superimposed onto an empty communication slot at an existing communication interface between the units if there is such an empty slot.
The technique of Japanese Patent Laid-Open No. H05-324375(1993) has a problem in that circuitry is complicated. Specifically, this technique requires circuitry configured to monitor the communication at the existing communication interface to detect whether or not there is a sufficiently large empty slot for the superimposition of the diagnosis information, and superimpose the diagnosis information.